M-Enterococcus HiVeg™ Agar Base

Principle and Interpretation

M-Enterococcus HiVeg Agar Base is prepared by using HiVeg hydrolysate instead of Casein enzymic hydrolysate thus making the medium BSE/TSE risks free. This medium is the modification of M-Enterococcus Agar Base developed by Slanetz et al (1). Slanetz and Bartley (2) modified it by the addition of Triphenyl Tetrazolium Chloride (TTC) and found that this medium proved to be superior membrane filtration medium for enumeration of Enterococci. Increased recovery and larger colonies were obtained by incubating the inoculated membranes directly on the agar surface instead of on pads saturated with liquid medium. Burkwell and Hartman (3) used polysorbate 80 (0.5 ml/liter) and sodium carbonate (2 ml of a 10% aqueous solution per liter) to increase sensitivity for direct plating of foods and increasing colony size (4).

HiVeg hydrolysate and Papaic digest of soyabean meal, yeast extract, dextrose act as source of carbon, nitrogen and other essential growth nutrients. Sodium azide inhibits gram-negative organisms. TTC serves as a rapid indicator of bacterial growth which is reduced to insoluble formazan inside the bacterial cells and gives red colouration to colonies.